From 7c18973b42216f9c6956224776b12ada01d2a14d Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Wed, 6 Dec 2017 09:17:07 -0600 Subject: [PATCH] xfs_io: implement ranged fiemap query Currently the fiemap implementation of xfs_io doesn't support making ranged queries. This patch implements two optional arguments which take the starting offset and the length of the region to be queried. When the end of the requested region falls within an extent boundary then we print the whole extent (i.e. return all the information that the kernel has given us). When the end offset falls within a hole then the printed hole range is truncated to the requested one since we do not have information how long the hole is. Signed-off-by: Nikolay Borisov Reviewed-by: Eric Sandeen [sandeen: simplify/rewrite ranged logic] Reviewed-by: Nikolay Borisov Signed-off-by: Eric Sandeen --- io/fiemap.c | 81 +++++++++++++++++++++++++++++++++++++---------- man/man8/xfs_io.8 | 14 +++++++- 2 files changed, 78 insertions(+), 17 deletions(-) diff --git a/io/fiemap.c b/io/fiemap.c index bdcfacdb2..2f1265264 100644 --- a/io/fiemap.c +++ b/io/fiemap.c @@ -49,6 +49,8 @@ fiemap_help(void) " -l -- also displays the length of each extent in 512-byte blocks.\n" " -n -- query n extents.\n" " -v -- Verbose information\n" +" offset is the starting offset to map, and is optional. If offset is\n" +" specified, mapping length may (optionally) be specified as well." "\n")); } @@ -101,6 +103,7 @@ print_verbose( char lbuf[48]; char bbuf[48]; char flgbuf[16]; + int num_printed = 0; llast = BTOBBT(last_logical); lstart = BTOBBT(extent->fe_logical); @@ -118,14 +121,15 @@ print_verbose( flg_w, _("FLAGS")); } - if (lstart != llast) { + if (lstart > llast) { print_hole(foff_w, boff_w, tot_w, cur_extent, 0, false, llast, lstart); cur_extent++; + num_printed++; } if (cur_extent == max_extents) - return 1; + return num_printed; snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", (unsigned long long)lstart, lstart + len - 1ULL); @@ -135,7 +139,9 @@ print_verbose( printf("%4d: %-*s %-*s %*llu %*s\n", cur_extent, foff_w, lbuf, boff_w, bbuf, tot_w, (unsigned long long)len, flg_w, flgbuf); - return 2; + num_printed++; + + return num_printed; } static int @@ -149,29 +155,33 @@ print_plain( __u64 llast; __u64 block; __u64 len; + int num_printed = 0; llast = BTOBBT(last_logical); lstart = BTOBBT(extent->fe_logical); len = BTOBBT(extent->fe_length); block = BTOBBT(extent->fe_physical); - if (lstart != llast) { + if (lstart > llast) { print_hole(0, 0, 0, cur_extent, lflag, true, llast, lstart); cur_extent++; + num_printed++; } if (cur_extent == max_extents) - return 1; + return num_printed; printf("\t%d: [%llu..%llu]: %llu..%llu", cur_extent, (unsigned long long)lstart, lstart + len - 1ULL, (unsigned long long)block, block + len - 1ULL); + num_printed++; + if (lflag) printf(_(" %llu blocks\n"), (unsigned long long)len); else printf("\n"); - return 2; + return num_printed; } /* @@ -222,7 +232,7 @@ fiemap_f( char **argv) { struct fiemap *fiemap; - int last = 0; + int done = 0; int lflag = 0; int vflag = 0; int fiemap_flags = FIEMAP_FLAG_SYNC; @@ -235,9 +245,15 @@ fiemap_f( int boff_w = 16; int tot_w = 5; /* 5 since its just one number */ int flg_w = 5; - __u64 last_logical = 0; + __u64 last_logical = 0; /* last extent offset handled */ + off64_t start_offset = 0; /* mapping start */ + off64_t length = -1LL; /* mapping length */ + off64_t range_end = -1LL; /* mapping end*/ + size_t fsblocksize, fssectsize; struct stat st; + init_cvtnum(&fsblocksize, &fssectsize); + while ((c = getopt(argc, argv, "aln:v")) != EOF) { switch (c) { case 'a': @@ -257,6 +273,27 @@ fiemap_f( } } + /* Range start (optional) */ + if (optind < argc) { + start_offset = cvtnum(fsblocksize, fssectsize, argv[optind]); + if (start_offset < 0) { + printf("non-numeric offset argument -- %s\n", argv[optind]); + return 0; + } + last_logical = start_offset; + optind++; + } + + /* Range length (optional if range start was specified) */ + if (optind < argc) { + length = cvtnum(fsblocksize, fssectsize, argv[optind]); + if (length < 0) { + printf("non-numeric len argument -- %s\n", argv[optind]); + return 0; + } + range_end = start_offset + length; + } + map_size = sizeof(struct fiemap) + (EXTENT_BATCH * sizeof(struct fiemap_extent)); fiemap = malloc(map_size); @@ -269,12 +306,11 @@ fiemap_f( printf("%s:\n", file->name); - while (!last && (cur_extent != max_extents)) { - + while (!done) { memset(fiemap, 0, map_size); fiemap->fm_flags = fiemap_flags; fiemap->fm_start = last_logical; - fiemap->fm_length = -1LL; + fiemap->fm_length = range_end - last_logical; fiemap->fm_extent_count = EXTENT_BATCH; ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap); @@ -314,13 +350,23 @@ fiemap_f( cur_extent += num_printed; last_logical = extent->fe_logical + extent->fe_length; + /* Kernel has told us there are no more extents */ if (extent->fe_flags & FIEMAP_EXTENT_LAST) { - last = 1; + done = 1; + break; + } + + /* We have exhausted the requested range */ + if (last_logical >= range_end) { + done = 1; break; } - if (cur_extent == max_extents) + /* We have printed requested nr of extents */ + if (cur_extent == max_extents) { + done = 1; break; + } } } @@ -336,9 +382,12 @@ fiemap_f( return 0; } - if (cur_extent && last_logical < st.st_size) + /* Print last hole to EOF or to end of requested range */ + range_end = min((uint64_t)range_end, st.st_size); + + if (cur_extent && last_logical < range_end) print_hole(foff_w, boff_w, tot_w, cur_extent, lflag, !vflag, - BTOBBT(last_logical), BTOBBT(st.st_size)); + BTOBBT(last_logical), BTOBBT(range_end)); out: free(fiemap); @@ -353,7 +402,7 @@ fiemap_init(void) fiemap_cmd.argmin = 0; fiemap_cmd.argmax = -1; fiemap_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK; - fiemap_cmd.args = _("[-alv] [-n nx]"); + fiemap_cmd.args = _("[-alv] [-n nx] [offset [len]]"); fiemap_cmd.oneline = _("print block mapping for a file"); fiemap_cmd.help = fiemap_help; diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8 index 9bf1a4783..fabf92f36 100644 --- a/man/man8/xfs_io.8 +++ b/man/man8/xfs_io.8 @@ -304,11 +304,23 @@ Prints the block mapping for the current open file. Refer to the .BR xfs_bmap (8) manual page for complete documentation. .TP -.BI "fiemap [ \-alv ] [ \-n " nx " ]" +.BI "fiemap [ \-alv ] [ \-n " nx " ] [ " offset " [ " len " ]]" Prints the block mapping for the current open file using the fiemap ioctl. Options behave as described in the .BR xfs_bmap (8) manual page. +.PP +.RS +Optionally, this command also supports passing the start offset +from where to begin the mapping and the length of that region. +The kernel will return any full extents which intersect with the requested +range, and the +.B fiemap +command will print them in their entirety. If the requested range starts +or ends in a hole, +.B fiemap +will print the hole, truncated to the requested range. +.RE .TP .BI "fsmap [ \-d | \-l | \-r ] [ \-m | \-v ] [ \-n " nx " ] [ " start " ] [ " end " ] Prints the mapping of disk blocks used by the filesystem hosting the current -- 2.47.2